根据降水量观测记录及史料,建立了我国 1 1 0°E以东 35个站 1 880～ 1 998年完整的四季及年降水量序列。1 880～ 1 899年主要依靠史料及少数站降水量观测 ;1 90 0～ 1 950年根据降水量等级图,并用史料插补 ;1 951年以后完全是降水量观测资料。 3段时间降水量观测记录分别占2 2 .6%、 69.0 %及 1 0 0 %。史料部分利用了近 30多年公布的 1 5种经过整编的旱涝记载。本文介绍了建立序列的方法及可能包含的误差大小。年降水量的功率谱分析结果显示年降水量的突出周期有两个,分别是 3.3a和 2 6.7a,前者可能与 ENSO的影响有关,而后者则说明我国降水有显著的年代际尺度的变化。近百年来我国年降水量变化趋势,只有约 +0 .1 % /1 0 0 a。

The seasonal and annual precipitation series of 35 stations over eastern China were established using the observations as well as proxy data. All the time series cover the period 1880～1998. During the period 1880～1889, the observed precipitation records are available only for several stations. The huge gap in the data were filled using the historical materials which are used in the past climate reconstruction fruitfully. During the period 1900～1950, the Precipitation Grade Map was applied, and some data gaps were resolved using the documentary evidence too. Since 1951, precipitation observations have been available. During the 3 different periods of time, the observations account for 22 6%, 69 0% and 100% of the total amount of data respectively. All documentary evidence used in this paper is transformed into 5 precipitation categories for every season. The standard is the same as that of used by the China Flood/drought Category Map for the Last Five Centuries, i.e., category 1 is heavy flood, 2 is flood, 3 is normal, 4 is drought and 5 is heavy drought. The frequency of the categories is 1/8 for categories 1 and 5 and 1/4 for the three others. Then, all precipitation categories are transformed into the precipitation amount by the specific functions determined using the recent observed data. Thus, the seasonal precipitation data of all the 35 stations are obtained, and added into the annual amount in the order of spring, summer, autumn and winter. And the possible errors in the transformation are estimated, in averaging less than 28% of the actual rainfall values. The variability of the annual precipitation is preliminarily analyzed. There are no obvious trend, only +0 1%/100a when calculated using the data of whole period 1880～1998. However, there are significant low frequency variations for both the seasonal and annual precipitation series as shown in Figure 2. Power spectral analysis demonstrated that there are evident cycles of 3 3a and 26 7a. The annual time scale period of 3.3a may be related to the ENSO, and the period of 26 7a suggests that there is strong interdecadal variability in the precipitation of China. The significant rainfall variations in the past several decades may be caused by the interdecadal changes, and have no strong association with the global climate trends as expected in some diagnostic and modeling studies.